Fuel and vehicle specification equipment.

Abstract

DEPCT67 This fuel characterization device determines the composition of the stored liquefied natural gas. The fuel in the tank is for the engine. The fuel specification device has approximate units of measurement. The methane number of liquefied natural gas is estimated using the first approximation method when the engine is running. The methane number of liquefied natural gas is estimated using a second estimation method that differs from the previous estimation method. First, when the engine is restarted from a stopped state, the control unit that manages the notification device will respond. In order to provide notification indicating that a change in properties has occurred in liquefied natural gas, if the number... The methane content of liquefied natural gas, estimated by first or second estimation methods, is less than the threshold. change;

Description

Fuel property determination device and vehicle

[0001] The present disclosure relates to a fuel property determining device and a vehicle.

[0002] For example, it is known that liquefied natural gas (hereinafter referred to as LNG fuel) is used as engine fuel in vehicles and the like (see, for example, Patent Document 1).

[0003] Japanese Patent Application Publication No. 2021-92202

[0004] LNG fuel is primarily composed of methane, and also contains other components such as ethane, propane, and butane. Methane, which has the lowest boiling point, vaporizes first. This causes the properties of the LNG fuel stored in the tank to change (hereinafter referred to as "property change"), making the engine more susceptible to knocking.

[0005] Therefore, in order to take measures against changes in the properties of LNG fuel (for example, consuming or replacing the fuel), it is desirable for users to recognize changes in the properties of LNG fuel at more appropriate times.

[0006] An object of one aspect of the present disclosure is to provide a fuel property determination device and a vehicle that allow a user to recognize changes in the properties of LNG fuel at a more appropriate time.

[0007] A fuel property determination device according to one aspect of the present disclosure is a fuel property determination device that determines the components of liquefied natural gas stored in a tank as engine fuel, and includes an estimation unit that estimates the methane number of the liquefied natural gas using a first estimation method when the engine is running, and that estimates the methane number of the liquefied natural gas using a second estimation method different from the first estimation method when the engine is restarted from a stopped state, and a control unit that controls a notification device to notify that the properties of the liquefied natural gas have changed when the methane number of the liquefied natural gas estimated by the first estimation method or the second estimation method is below a threshold value.

[0008] A vehicle according to an aspect of the present disclosure includes a fuel property determination device according to an aspect of the present disclosure.

[0009] According to the present disclosure, a user can recognize changes in the properties of LNG fuel at a more appropriate time.

[0010] Fig. 1 is a diagram schematically illustrating an example of the configuration of a fuel property determining device according to an embodiment of the present disclosure. Fig. 2 is a diagram schematically illustrating an image of calculation of a correction term. Fig. 3 is a diagram illustrating an example of an index value and a correction index value indicating an ignition retard control amount in a cylinder. Fig. 4 is a flowchart illustrating an example of a first estimation method. Fig. 5 is a flowchart illustrating an example of the operation of the fuel property determining device according to an embodiment of the present disclosure.

[0011] Hereinafter, embodiments of the present disclosure will be described with reference to the drawings.

[0012] First, the configuration of a fuel property determining device 100 according to this embodiment will be described with reference to Fig. 1. Fig. 1 is a diagram showing a schematic configuration example of the fuel property determining device 100.

[0013] 1 is mounted on a vehicle (not shown) equipped with an engine (not shown) powered by LNG fuel, for example. As described above, LNG fuel contains multiple components (e.g., methane, ethane, propane, butane, etc.) with different boiling points, and is a fuel that can undergo property changes (e.g., changes in the ratios of multiple components, which may also be referred to as component change or heavier fueling).

[0014] The vehicle is equipped with, for example, an LNG fuel supply system (not shown) that supplies LNG fuel to an engine. Although not shown, the LNG fuel supply system includes, for example, an LNG tank that stores LNG fuel, an LNG fuel supply line, a vaporizer that vaporizes the LNG fuel, a shutoff valve that opens and closes the LNG fuel supply line, and an LNG regulator that reduces the pressure of the LNG fuel vaporized in the vaporizer. The LNG fuel supply line connects the LNG tank to the LNG regulator via the shutoff valve, and connects the LNG regulator to the engine. The engine is a spark-ignition internal combustion engine that ignites and burns the vaporized LNG fuel. The engine has multiple cylinders.

[0015] In addition to the LNG fuel supply system, the vehicle may also be equipped with a CNG fuel supply system (not shown) that supplies compressed natural gas (CNG) to the engine. Although not shown, the CNG fuel supply system includes, for example, a CNG tank that stores CNG fuel, a CNG fuel supply line, a shutoff valve that opens and closes the CNG fuel supply line, and a CNG regulator that reduces the pressure of the CNG fuel. The CNG fuel supply line connects the CNG tank to the engine via the shutoff valve and the CNG regulator. When the vehicle is equipped with both the LNG fuel supply system and the CNG fuel supply system, for example, when the methane number of the LNG fuel decreases and the engine is in a high-load state, it becomes possible to switch from LNG fuel to CNG fuel.

[0016] The timing device 10 , remaining amount sensor 20 , and notification device 60 shown in FIG. 1 are mounted on the vehicle together with the fuel property determining device 100 and are electrically connected to the fuel property determining device 100 .

[0017] The timing device 10 measures time (including, for example, year, month, day, hour, and minute). The measurement results of the timing device 10 (hereinafter referred to as date and time information) are output from the timing device 10 to the fuel property determining device 100.

[0018] In this embodiment, the timing device 10 is separate from the fuel property determining device 100 , but the fuel property determining device 100 may have the functions of the timing device 10 .

[0019] The remaining amount sensor 20 detects the remaining amount of LNG fuel stored in the LNG tank. The detection result of the remaining amount sensor 20 (hereinafter referred to as remaining amount information) is output from the remaining amount sensor 20 to the fuel property determination device 100. Note that the remaining amount may be the amount of stored LNG fuel or the ratio of the stored amount to the total capacity of the LNG tank.

[0020] The knock sensor 30 detects engine knocking. The knock sensor 30 has, for example, a piezoelectric element that detects vibrations of an engine block (not shown). The detection result of the knock sensor 30 (hereinafter referred to as knocking information) is output from the knock sensor 30 to the fuel property determining device 100.

[0021] The crank angle sensor 40 detects the engine speed. The detection result of the crank angle sensor 40 (hereinafter referred to as "speed information") is output from the crank angle sensor 40 to the fuel property determining device 100.

[0022] The torque sensor 50 detects the engine load based on, for example, the degree of rotational fluctuation of the crankshaft (not shown). Note that the engine load may also be detected based on the accelerator pedal opening or the throttle opening. The detection result of the torque sensor 50 (hereinafter referred to as load information) is output from the torque sensor 50 to the fuel property determining device 100.

[0023] The notification device 60 issues a notification (hereinafter referred to as a warning notification) that the properties of the LNG fuel have changed. The notification device 60 is, for example, an indicator lamp provided in a position inside the vehicle that is easily visible to vehicle occupants (an example of a user). In this case, the flashing of the indicator lamp indicates that the properties of the LNG fuel have changed.

[0024] The fuel property determination device 100 is a device that determines whether the properties of the LNG fuel stored in the LNG tank have changed, and controls the notification device 60 to issue a warning notification if the properties of the LNG fuel have changed.

[0025] Although not shown in the drawings, the fuel property determination device 100 includes, as hardware, for example, a central processing unit (CPU), read-only memory (ROM) storing a computer program, random access memory (RAM) serving as a working memory, input ports, output ports, etc. The functions of the fuel property determination device 100 described below are realized by the CPU reading a computer program from the ROM and executing it in the RAM. The fuel property determination device 100 may also be realized by, for example, an electronic control unit (ECU).

[0026] As shown in FIG. 1 , the fuel property determining device 100 includes an estimation unit 110 and a control unit 120 .

[0027] When the engine is running, the estimation unit 110 estimates the methane number of the LNG fuel (hereinafter also simply referred to as the methane number) using the first estimation method.

[0028] The details of the first estimation method will be described later, but to briefly explain, in the first estimation method, the estimation unit 110 calculates an ignition retard control amount to avoid engine knocking, and estimates the methane number of the LNG fuel based on an index value indicating the ignition retard control amount.

[0029] On the other hand, when the engine is restarted from a stopped state, the estimation unit 110 estimates the methane number of the LNG fuel using a second estimation method that is different from the first estimation method.

[0030] The second estimation method will be described in detail later, but to briefly explain, in the second estimation method, the estimation unit 110 estimates the methane number of the LNG fuel based on the remaining amount of LNG fuel in the LNG tank when the engine is stopped and the engine stop time (the elapsed time from when the engine is stopped until it is restarted).

[0031] The control unit 120 determines whether the methane number of the LNG fuel estimated by the first estimation method or the second estimation method (hereinafter referred to as the estimated methane number) is less than a predetermined threshold value.

[0032] If the estimated methane number is less than the threshold value, the control unit 120 controls the notification device 60 to issue a warning notification.

[0033] For example, if the notification device 60 is an indicator lamp, the control unit 120 controls the indicator lamp to flash at a predetermined time interval, so that the indicator lamp flashes, allowing a user (e.g., a vehicle occupant) to easily recognize that the LNG fuel has changed in properties (which may be referred to as becoming heavier).

[0034] If the estimated methane number is not less than the threshold value, the control unit 120 does not control the notification device 60 .

[0035] Next, the first estimation method will be described in detail.

[0036] First, the estimation unit 110 calculates an ignition retard control amount for each of the plurality of cylinders based on the knocking information acquired from the knock sensor 30. Here, the ignition retard control amount refers to an advance value Δθ (°) for the ignition timing. The estimation unit 110 corrects the ignition timing of the spark plug for each cylinder based on the advance value (ignition retard control amount).

[0037] Here, the estimation unit 110 does not correct the ignition timing when the advance angle value Δθ is 0. On the other hand, the estimation unit 110 does not correct the ignition timing when the advance angle value Δθ is −Δθ １ If the ignition timing is Δθ １ The ignition timing is corrected so that it is delayed by Δθ １ The estimation unit 110 also estimates that the advance angle Δθ is −Δθ ２ If the ignition timing is greater than the predetermined ignition timing, ２ The ignition timing is corrected so that it is delayed by Δθ ２ (The advance angle is retarded.) Here, the magnitude of each advance angle value Δθ is 0>−Δθ １ >-Δθ ２ If so, the advance value (ignition retard control amount) -Δθ １ is said to be lower than the lead angle value 0. Also, the lead angle value -Δθ ２ is the lead angle value - Δθ １ It is said to be lower than

[0038] Next, the estimation unit 110 calculates an average value of the ignition retard control amounts for each of two or more cylinders that are lower than the other cylinders among the acquired ignition retard control amounts for each of the plurality of cylinders.

[0039] For example, when the advance values ​​(ignition retard control amounts) of the respective cylinders are 0, −Δθ １ , ..., -Δθ ｎ－ｋ , -Δθ ｎ－（ｋ－１） , ..., -Δθ ｎ－１ , -Δθ ｎ and the magnitude of each advance angle value is 0>-Δθ １ >, …, −Δθ －ｋ >-Δθ ｎ－（ｋ－１） , …, >-Δ ｎ-１ >-Δθ ｎ(n and k are natural numbers), the estimation unit 110 calculates the advance value (-Δθ) of each of the k cylinders that is lower than the other cylinders. ｎ－（ｋ－１） , ..., -Δθ ｎ－１ , -Δθ ｎ ) is divided by k to calculate an average value. In the following description, the average value of the advance values ​​for each of the k cylinders is referred to as an "index value."

[0040] Next, the estimation unit 110 calculates a correction term for correcting the index value. Fig. 2 is a diagram showing a schematic image of the calculation of the correction term.

[0041] As shown in FIG. 2, the estimation unit 110 calculates a correction term for the index value (average value) by referring to a correction map based on the engine speed indicated by the speed information obtained from the crank angle sensor 40 and the engine load indicated by the load information obtained from the torque sensor 50.

[0042] The correction map is stored in a storage unit (e.g., a ROM, not shown) of the fuel property determining device 100. The correction map is a map that indicates the relationship between the engine speed and engine load and the correction amount, and can be obtained by experiment or simulation.

[0043] The correction term is a parameter for correcting the index value (average value) when the operating state (engine speed, engine load) is acquired to the index value of the reference operating state (engine speed: 1000 rpm, engine load: 100 Nm).

[0044] Next, the estimation unit 110 calculates a correction index value by multiplying the index value (average value) by a correction term. Fig. 3 shows examples of the index value (average value) indicating the ignition retard control amount for a cylinder and the correction index value.

[0045] Next, the estimation unit 110 estimates the methane number based on the calculated corrected index value by referring to a predetermined conversion table. Here, the conversion table refers to a table that shows the relationship between the corrected index value and the methane number.

[0046] The flow of the first estimation method described above is summarized in Fig. 4. The flow of Fig. 4 is started, for example, after the engine is started, and is executed at predetermined time intervals while the engine is running.

[0047] First, the estimation unit 110 calculates an ignition retard control amount (advance angle value) based on knocking information (step S1).

[0048] Next, the estimation unit 110 calculates an index value by calculating the average value of the advance angle values ​​(ignition retard control amounts) for each of the acquired multiple cylinders, for two or more cylinders that are lower than the other cylinders (step S2).

[0049] Next, the estimation unit 110 calculates a correction term for the index value by referring to the correction map based on the rotation speed information and load information, and calculates a modified index value by multiplying the calculated correction term by the index value (step S3).

[0050] Next, the estimation unit 110 estimates the methane number based on the calculated correction index value by referring to a predetermined conversion table (step S4).

[0051] The methane number estimated in this manner is compared with a threshold value by the control unit 120.

[0052] Next, the second estimation method will be described in detail.

[0053] Before executing the second estimation method, the estimation unit 110 performs a preparation process. Specifically, when the engine in a running state is stopped, the estimation unit 110 acquires and stores date and time information, remaining amount information, and an estimated methane number at the time the engine was stopped. The estimated methane number stored here is the latest methane number estimated by the first estimation method described above. This estimated methane number is a value equal to or less than the initial value (the methane number when the LNG tank is filled with LNG fuel).

[0054] When the stopped engine is subsequently restarted, the estimation unit 110 acquires the date and time information of the engine restart. Then, the estimation unit 110 executes the second estimation method as follows.

[0055] First, the estimation unit 110 calculates the time from when the engine stopped to when it restarted (in other words, the time the engine was stopped; hereinafter referred to as the engine stop time) based on the date and time information when the engine stopped and the date and time information when the engine restarted.

[0056] Next, the estimation unit 110 determines a subtraction value by referring to a subtraction map (not shown) based on the calculated engine stop time and the remaining amount indicated in the remaining amount information at the time the engine was stopped.

[0057] The subtraction map is stored in a storage unit (e.g., a ROM, not shown) of the fuel property determining device 100. The subtraction map is a map showing the relationship between the engine stop time, the remaining amount, and the subtraction value (e.g., a table in which the subtraction value is determined corresponding to the value indicating the engine stop time and the value indicating the remaining amount), and can be obtained by experiment or simulation. In this subtraction map, the subtraction value is determined to be larger as the engine stop time is longer and the remaining amount is smaller.

[0058] Next, the estimation unit 110 estimates the methane number by subtracting the determined subtraction value from the estimated methane number stored when the engine was stopped (the estimated methane number obtained by the first estimation method).

[0059] The methane number estimated in this manner is compared with a threshold value by the control unit 120.

[0060] Next, the operation of the fuel property determining device 100 will be described with reference to Fig. 5. Fig. 5 is a flowchart showing an example of the operation of the fuel property determining device 100. The flow of Fig. 5 is started, for example, when the engine is started for the first time after the LNG tank is filled with LNG fuel. Note that, as an example, it is assumed here that the estimation unit 110 determines (detects) whether the engine has started and whether the engine has stopped based on a predetermined operation by a vehicle occupant (for example, turning an engine start switch on / off).

[0061] First, the estimation unit 110 determines whether the started engine has stopped (step S11).

[0062] If the engine has stopped (step S11: YES), the flow proceeds to step S15, which will be described later.

[0063] If the engine is not stopped (step S11: NO), the estimation unit 110 estimates the methane number using the first estimation method described above (step S12).

[0064] Next, the control unit 120 determines whether the estimated methane number is less than a threshold value (step S13).

[0065] If the estimated methane number is not less than the threshold value (step S13: NO), the flow returns to step S11.

[0066] If the estimated methane number is less than the threshold value (step S13: YES), the control unit 120 controls the notification device 60 to issue a warning notification (step S14). As a result, the notification device 60 issues a warning notification, allowing the user (vehicle occupant) to recognize that the properties of the LNG fuel have changed.

[0067] If the engine has stopped (step S11: YES), the estimation unit 110 acquires and stores the date and time information at the time the engine stopped, remaining amount information, and estimated methane number (estimated methane number obtained by the first estimation method) (step S15).

[0068] Thereafter, the estimation unit 110 determines whether the stopped engine has been restarted (step S16).

[0069] If the engine has not restarted (step S16: NO), the flow returns to step S16.

[0070] If the engine is restarted (step S16: YES), the estimation unit 110 acquires date and time information when the engine is restarted (step S17).

[0071] Next, the estimation unit 110 estimates the methane number using the second estimation method described above, based on the date and time information, remaining amount information, and estimated methane number when the engine was stopped, the date and time information when the engine was restarted, and the subtraction map (step S18).

[0072] Next, the control unit 120 determines whether the estimated methane number is less than a threshold value (step S19).

[0073] If the estimated methane number is not less than the threshold value (step S19: NO), the flow returns to step S11. In this case, in the subsequent first estimation method (step S12), estimation may be performed based on the methane number estimated by the second estimation method (step S18).

[0074] If the estimated methane number is less than the threshold value (step S19: YES), the control unit 120 controls the notification device 60 to issue a warning notification (step S14). As a result, the notification device 60 issues a warning notification, allowing the user (vehicle occupant) to recognize that the properties of the LNG fuel have changed.

[0075] As described above, the fuel property determination device 100 of this embodiment is a device that determines the components of LNG fuel stored in an LNG tank as engine fuel, and is characterized by having an estimation unit 110 that estimates the methane number of the LNG fuel using a first estimation method when the engine is running, and that estimates the methane number of the LNG fuel using a second estimation method that is different from the first estimation method when the engine is restarted from a stopped state, and a control unit 120 that controls the notification device 60 to issue a notification that the properties of the LNG fuel have changed when the methane number estimated by the first estimation method or the second estimation method is below a threshold value.

[0076] This feature allows the methane number to be estimated using different methods when the engine is running and when it is stopped, improving the reliability of the estimated methane number and enabling more accurate determination of whether the properties of the LNG fuel have changed. This allows the user to recognize that the properties of the LNG fuel have changed at a more appropriate time and to take measures to deal with the change in properties (such as consuming or refilling LNG fuel).

[0077] Furthermore, the first estimation method allows for an appropriate spark advance to be set based on the estimated methane number. This makes it possible to prevent excessive knocking and engine malfunctions, and also to maintain engine performance at an appropriate level.

[0078] In the first estimation method, the advance value (ignition retard control amount) for each of the plurality of cylinders is acquired, and the average of the advance values ​​for two or more cylinders that are lower than the other cylinders among the acquired advance values ​​for each of the plurality of cylinders is calculated as the index value. This makes it possible to reliably detect changes in the properties of the LNG fuel, thereby improving the reliability of detecting a decrease in the methane number.

[0079] In the first estimation method, the methane number of the LNG fuel is estimated based on an index value corrected based on the engine speed and the engine load (i.e., the corrected index value). This standardizes the index value, thereby improving the accuracy of estimating the methane number.

[0080] The present disclosure is not limited to the above-described embodiment, and various modifications are possible without departing from the spirit of the present disclosure. Modifications will be described below.

[0081] [Variation 1] In the embodiment, a plurality of subtraction maps used in the second estimation method may be prepared according to the magnitude of the estimated methane number at the time of engine stop, and each subtraction map may be set so that the subtraction value is different even for the same remaining amount and the same engine stop time.

[0082] [Modification 2] In the embodiment, the case where the estimation unit 110 corrects the index value based on the correction term or the like and estimates the methane number using the corrected index value obtained thereby has been described as an example, but the present invention is not limited to this. For example, the estimation unit 110 may estimate the methane number using the index value before correction.

[0083] [Modification 3] In the embodiment, the control unit 120 controls the notification device 60 as an example. However, other devices may be controlled in addition to the notification device 60. For example, when the estimated methane number falls below a threshold and the engine is in a high-load state, the control unit 120 may control the shutoff valves of the LNG fuel supply system and the CNG fuel supply system so as to close the LNG fuel supply path and open the CNG fuel supply path. This causes a switch from LNG fuel to CNG fuel, making it possible to suppress excessive knocking and engine malfunction.

[0084] [Variation 4] In the embodiment, the notification device 60 is an indicator lamp provided in the vehicle cabin, but is not limited thereto. For example, the notification device 60 may be a display that displays an image (an example of a warning notification) indicating that the properties of the LNG fuel have changed, or a speaker that outputs a sound (an example of a warning notification) indicating that the properties of the LNG fuel have changed. Furthermore, the warning notification may be both an image display and a sound output.

[0085] [Modification 5] In the embodiment, the fuel property determining device 100 is mounted on a vehicle, but the present invention is not limited to this. The fuel property determining device 100 may be mounted on a moving body other than a vehicle (for example, a ship, etc.), or on a machine equipped with a stationary engine, etc.

[0086] [Variation 6] In the embodiment, the torque sensor 50 is used to acquire the engine load, but the present invention is not limited to this. For example, the fuel property determining device 100 may estimate the engine load from the intake manifold pressure. In this case, the intake manifold pressure is detected by a pressure sensor.

[0087] This application is based on a Japanese patent application (Patent Application No. 2021-170415) filed on October 18, 2021, the contents of which are incorporated herein by reference.

[0088] The fuel property determination device and vehicle of the present disclosure are useful when liquefied natural gas containing multiple components with different boiling points is used as engine fuel.

[0089] REFERENCE SIGNS LIST 10 Timing device 20 Remaining amount sensor 30 Knock sensor 40 Crank angle sensor 50 Torque sensor 60 Notification device 100 Fuel property determination device 110 Estimation unit 120 Control unit

Claims

DEPCT671. Fuel characterization device that determines the composition of liquefied natural gas (LNG) stored as fuel for engines in tanks. The fuel characterization device consists of an estimation unit that estimates the methane number of LNG using the first estimation method when the engine is running and estimates the methane number of LNG using a second estimation method that differs from the first method when the engine is restarted from a standstill; and a control unit that controls the notification device in such a way that the notification device provides a notification indicating that a change in character has occurred in the LNG if the methane number estimated by the first or second estimation method is less than the threshold for change.The fuel specification device under Claim 1, in which the estimation unit calculates the amount of ignition delay control to avoid engine knocking and estimates the methane number of liquefied natural gas (LNG) based on an index indicating the amount of ignition delay control, and in the second estimation method, the estimation unit estimates the methane number of LNG based on the residual LNG and the engine stop time, where residual LNG is the amount of LNG remaining in the tank when the engine is stopped.

3. The fuel specification device under Claim 1, in which the estimation unit estimates the methane number of LNG by the second estimation method based on the methane number of LNG estimated by the first estimation method.

4. The fuel specification device under Claim 1, in which the estimation unit estimates the methane number of LNG by the first estimation method based on the methane number of LNG estimated by the second estimation method. 5.Fuel specification device under Claim 1 where the device is indicated by an indicator light provided in the interior of the vehicle in which the engine is installed and the control unit causes the indicator light to flash at a predetermined interval.

6. Vehicles equipped with a fuel specification device under Claim 1;